This article offers a justification for a set of principles that constitute the ethical underpinnings of forensic psychiatry. Like professional ethics in general, the principles are based on the particular societal functions performed by forensic psychiatrists and result in the intensification of obligations to promote certain important moral values. For forensic psychiatrists, the primary value of their work is to advance the interests of justice. The two principles on which that effort rests are truth-telling and respect for persons. In the same manner as other physicians who perform functions outside of the usual clinical context (e.g., clinical researchers), forensic psychiatrists cannot simply rely on general medical ethics, embedded as they are in the doctor-patient relationship--which is absent in the forensic setting. Indeed, efforts to retain some residuum of that relationship and its associated ethical principles are likely to create confusion in the minds of both forensic psychiatrists and their evaluees and to heighten the problems of double agency. A virtue of this approach is the clear distinction it offers between clinical and forensic roles.